import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Iterator;
import java.util.Set;

public class MultiplexerTimeServer implements Runnable {

    private Selector selector;

    private ServerSocketChannel serverSocketChannel;

    private volatile boolean stop;

    public MultiplexerTimeServer(int port){
        try{
            selector = Selector.open();
            serverSocketChannel = ServerSocketChannel.open();
            serverSocketChannel.configureBlocking(false);
            serverSocketChannel.bind(new InetSocketAddress(port),1024);
            serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
            System.out.println("the server is start in port "+ port);
        }catch (Exception e){
            e.printStackTrace();
            System.exit(1);
        }
    }
    public void stop(){
        this.stop = true;
    }

    @Override
    public void run() {
        while (!stop){
            try{
                selector.select(1000);
                Set<SelectionKey> selectionKeys = selector.selectedKeys();
                Iterator<SelectionKey> iterator = selectionKeys.iterator();
                SelectionKey key = null;
                while (iterator.hasNext()){
                    key = iterator.next();
                    iterator.remove();
                    try {
                        handleInput(key);
                    }catch (Exception e){
                        if(key != null){
                            key.cancel();
                            if(key.channel() != null){
                                key.channel().close();
                            }
                        }
                    }
                }
            }catch (Throwable t){
                t.printStackTrace();
            }
        }
        if (selector != null){
            try {
                selector.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    private void handleInput(SelectionKey key)throws  IOException{
        if(key.isValid()){
            if(key.isAcceptable()){
                ServerSocketChannel ssc = (ServerSocketChannel)key.channel();
                SocketChannel sc = ssc.accept();
                sc.configureBlocking(false);
                sc.register(selector,SelectionKey.OP_READ);
            }
            if(key.isReadable()){
                  SocketChannel sc = (SocketChannel)key.channel();
                  ByteBuffer readBuffer = ByteBuffer.allocate(1024);
                  int readBytes = sc.read(readBuffer);
                  if(readBytes > 0){
                        readBuffer.flip();
                        byte [] bytes = new byte[readBuffer.remaining()];
                        readBuffer.get(bytes);
                        String body = new String(bytes,"UTF-8");
                        System.out.println(("服务端收到信息：" + body));
                        String currentTime = "ORDER".equalsIgnoreCase(body)?new Date(System.currentTimeMillis()).toString():"BAD ORDER";
                        doWrite(currentTime,sc);
                  }else if(readBytes < 0 ){
                      key.cancel();
                      sc.close();
                  }else {
                  }
            }
        }
    }

    private void doWrite(String response,SocketChannel sc)throws  IOException{
        if(response != null && response.trim().length() > 0){
            byte[] bytes = response.getBytes();
            ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
            byteBuffer.put(bytes);
            byteBuffer.flip();
            sc.write(byteBuffer);
        }
    }
}
